CCNA IP Routing Practice Test 17 — 15 Questions

Question 1

Exhibit: A static route to 172.16.40.0/24 is configured, but traffic still follows the default route. Which two explanations are plausible?

Accepted Answer

The next hop for the static route may not be reachable. If a static route points to an unreachable next hop or the outgoing interface is down, the route may not be installed as usable. In that case the router can still use a less specific route such as the default route.

Answer

The default route always overrides more specific routes

Answer

Static routes require a metric lower than 1

Answer

The destination prefix must be configured under router ospf first

Question 2

A router has learned route 172.16.50.0/24 from OSPF with cost 20 and also has a static route to the same prefix with administrative distance 5. Which two statements are correct about route selection?

Accepted Answer

The static route is installed because it has the lower administrative distance. When the same prefix is learned from different routing sources, the router first compares administrative distance (AD). The static route with AD 5 wins over OSPF with AD 110, so option A is correct. Option C is correct because if the static route is removed, the OSPF route becomes the next best candidate and is installed. Option B is wrong since AD is compared before metrics like OSPF cost; a lower cost does not override a lower AD. Option D is wrong because only one route is installed per destination based on AD, not both.

Answer

The OSPF route is installed because cost 20 is lower than metric 0

Answer

Both routes are installed as equal-cost paths automatically

Question 3

A static default route is configured on R1 toward ISP-A, and a second default route toward ISP-B is configured with a higher administrative distance. Which two statements are correct during normal operation and after ISP-A failure?

Accepted Answer

The route through ISP-A is preferred during normal operation. This is a classic floating static design. The lower-AD default route is primary, and the higher-AD default waits in reserve.

Answer

Both defaults are always installed and used equally

Answer

The backup route is ignored permanently because only one default route can exist

Question 4

A network engineer needs a floating static route to back up an OSPF-learned route. Which two configurations are necessary for the static route to remain unused until OSPF fails?

Accepted Answer

Configure the static route with an administrative distance higher than 110. A floating static route requires an administrative distance higher than OSPF's default of 110 (option A) so that the static route is less preferred and remains inactive while OSPF is available. Additionally, the static route must point to a valid next-hop IP or exit interface (option B); without a valid next-hop, the route cannot be installed in the routing table and would never serve as a backup. Option C is incorrect because Cisco routers compare administrative distance before metric when routes come from different sources, so a lower metric cannot override the AD difference. Option D is wrong because a directly connected route (with no next-hop) would be treated as a connected route, not a static route, and would be preferred over OSPF due to its AD of 0, defeating the purpose of a floating backup.

Answer

Set the static route metric lower than the OSPF cost

Answer

Configure the route as directly connected with no next-hop information

Question 5

A branch router is running single-area OSPF. An engineer wants an interface to advertise its connected network into OSPF but must prevent hello packets from being sent on that LAN segment. Which two actions achieve that goal?

Accepted Answer

Enable OSPF on the interface or matching network statement. In OSPF, a passive interface still advertises the connected network but does not send or process hello packets. So the interface must participate in OSPF, and then it must be made passive.

Answer

Set the interface network type to point-to-point

Answer

Apply distribute-list out on the interface

Question 6

A route table shows both a default route and a more specific route to 192.168.50.0/24. Which two statements describe how packets destined for 192.168.50.25 are handled?

Accepted Answer

The router prefers the 192.168.50.0/24 route because it is the longest prefix match. Once routes are installed, packet forwarding follows longest prefix match. The /24 route is more specific than the default route, so traffic to 192.168.50.25 uses the /24 entry.

Answer

Administrative distance is compared before prefix length for forwarding decisions

Answer

The packet is load-balanced across both routes automatically

Question 7

A junior network engineer configured a floating static route on Router R1 to provide backup connectivity to a remote network 10.10.10.0/24. The primary connection uses OSPF. However, after the primary link fails, hosts on R1 cannot reach the remote network. The OSPF adjacency is down, and the floating static route is not appearing in the routing table. Based on the exhibit, what is the most likely cause of the issue?

Accepted Answer

The static route's next-hop becomes unreachable after the primary OSPF link fails.. The floating static route's next-hop becomes unreachable after the primary OSPF link fails. In the exhibit, the next-hop IP is likely configured to an address that is only reachable via OSPF; when that adjacency drops, the router has no route to the next-hop, so it cannot recursively resolve the static route. As a result, the route does not appear in the routing table. Option A is wrong because the route is present in the configuration (as a floating static route). Option C is wrong because the administrative distance of the floating static route is intentionally higher than OSPF's so that it only installs when OSPF fails; this is correct behavior. Option D is wrong because a default route would not override a more specific static route to 10.10.10.0/24.

Answer

The floating static route is missing from the configuration.

Answer

The administrative distance of the static route is too high.

Answer

The default route is overriding the static route to 10.10.10.0/24.

Question 8

A network administrator is troubleshooting a connectivity issue between two remote sites connected via a WAN link. Hosts on VLAN 10 at Site A (192.168.10.0/24) cannot ping the server at Site B (10.10.20.100). The router at Site A has a default route configured with the next-hop IP address 10.10.10.2. The administrator checks the routing table on Router A and notices that the default route is not installed. What is the most likely cause of the problem?

Accepted Answer

The next-hop router 10.10.10.2 is unreachable.. The default route uses a next-hop IP (10.10.10.2) and will only be installed in the routing table if that next-hop is reachable. Since the router’s routing table shows no default route, the most likely cause is that the next-hop 10.10.10.2 is unreachable, preventing the static route from being used. This explains why traffic fails despite the configuration.

Answer

The static route for 10.10.20.0/24 is missing from the routing table.

Answer

The GigabitEthernet0/0 interface is administratively down.

Answer

The default route is not configured; the gateway of last resort is missing.

Question 9

Which TWO statements about IPv4 and IPv6 static routing are correct?

Accepted Answer

A floating static route is configured with a higher administrative distance than the primary route.. A floating static route is configured with a higher administrative distance to serve as a backup when the primary route fails. Option D is correct because an IPv6 default static route uses the prefix ::/0 to match all destinations. Option A is incorrect because a default static route can be used independently of whether dynamic routing protocols are configured; it is simply a route with destination 0.0.0.0/0. Option C is incorrect because a floating static route must have a higher AD, not lower, than the primary route. Option E is incorrect because an IPv6 static route cannot specify an IPv4 address as the next-hop; it must use an IPv6 address or an outgoing interface.

Answer

A default static route is used when no dynamic routing protocols are configured.

Answer

A floating static route must have a lower administrative distance than the primary route.

Answer

An IPv6 static route can specify an IPv4 address as the next-hop.

Question 10

Which TWO statements accurately describe the behavior and configuration of floating static routes?

Accepted Answer

A floating static route uses an administrative distance greater than that of the primary dynamic route.. A floating static route serves as a backup by being configured with an administrative distance (AD) greater than that of the primary dynamic route, making it less preferred (option B). It remains inactive until the primary route is removed from the routing table, at which point the floating static route is installed (option D). Option A is wrong because it reverses the AD logic—a floating static route uses a higher, not lower, AD. Option C is incorrect because the AD of a floating static route is typically a value between 1 and 255, not necessarily less than 1. Option E is false because the AD of a floating static route is a fixed configured value and does not change automatically based on network conditions.

Answer

A floating static route is configured with a lower administrative distance than the primary dynamic route.

Answer

The administrative distance of a floating static route must be less than 1.

Answer

Floating static routes automatically adjust their administrative distance based on network conditions.

Question 11

An engineer is troubleshooting an OSPF adjacency between two directly connected routers, R1 and R2. R1 is configured with a passive-interface default under the OSPF process, and the interface connecting to R2 is not explicitly set to no passive-interface. The engineer runs a show ip ospf neighbor command on R1 and sees no neighbors. What is the most likely reason for the missing adjacency?

Accepted Answer

The passive-interface default command is preventing OSPF hellos on the interface.. The `passive-interface default` command under the OSPF process makes all interfaces passive by default, meaning OSPF Hellos are not sent unless explicitly overridden with `no passive-interface`. Since the interface to R2 was not configured with `no passive-interface`, R1 does not send Hellos, preventing adjacency. Option A is less likely because even if the network statement is correct, a passive interface still blocks Hellos. Option C is incorrect because OSPF automatically selects a router-id if not configured (highest loopback or interface IP), and a missing router-id does not prevent Hellos. Option D is unsupported by the scenario; no authentication mismatch is indicated.

Answer

The network statement does not match the interface IP address.

Answer

The router-id is not configured, so OSPF cannot form an adjacency.

Answer

There is an OSPF authentication mismatch between R1 and R2.

Question 12

An engineer is troubleshooting an OSPF adjacency issue between two Cisco routers, R1 and R2, connected via GigabitEthernet0/0 on both sides. Hosts on R1's LAN cannot ping hosts on R2's LAN. The engineer checks the OSPF neighbor state on R1 and sees the adjacency is stuck in EXSTART/EXCHANGE. The router IDs are 1.1.1.1 on R1 and 2.2.2.2 on R2, and both routers have a network statement for their directly connected subnet. What is the most likely cause of this problem?

Accepted Answer

There is an MTU mismatch between R1 and R2 on the GigabitEthernet0/0 interfaces.. The EXSTART/EXCHANGE state indicates that OSPF neighbors have progressed past the 2-Way state and are attempting to exchange Database Description (DBD) packets. An MTU mismatch on the directly connected GigabitEthernet0/0 interfaces prevents successful DBD exchange because the interface with the smaller MTU drops the larger DBD packet, causing the adjacency to remain stuck in EXSTART/EXCHANGE. Options A and C are incorrect because passive-interface default and area mismatches prevent the adjacency from reaching EXSTART/EXCHANGE (they block Hello exchange), and option D is incorrect because conflicting router IDs would prevent adjacency formation entirely, not result in a stuck EXSTART/EXCHANGE state.

Answer

The passive-interface default command is blocking OSPF Hellos on GigabitEthernet0/0.

Answer

The OSPF area configured on the interface does not match between R1 and R2.

Answer

The router IDs 1.1.1.1 and 2.2.2.2 are conflicting with each other.

Question 13

Which TWO statements correctly describe OSPFv2 router-id selection and verification in a single-area configuration?

Accepted Answer

When no 'router-id' is configured, a loopback interface with the highest IP address is preferred over a physical interface for the router-id.. OSPFv2 selects the router-ID based on the highest IP address of any loopback interface when no explicit 'router-id' is configured, making D correct. The 'show ip ospf' command displays the current router-ID, verifying choice E. Option A is incorrect because the router-ID is derived from IP addresses, not MAC addresses. Option B fails because changing the router-ID requires a reload or clearing the OSPF process to take effect. Option C is wrong because each router must have a unique router-ID; they do not need to match across the area.

Answer

The OSPF router-id is automatically derived from the MAC address of the first Ethernet interface.

Answer

If the router-id is changed using the 'router-id' command, the change takes effect immediately without any additional action.

Answer

The router-id must be the same on all routers in a single OSPF area.

Question 14

Which TWO statements correctly describe the behavior of the passive-interface command in single-area OSPFv2?

Accepted Answer

It prevents the router from sending Hello packets on the specified interface.. The passive-interface command in OSPFv2 suppresses all OSPF protocol packets (Hello, DD, LSR, LSU, LSAck) on the specified interface, preventing neighbor adjacency formation. However, the network prefix of that interface is still included in the router LSA and advertised through active interfaces to the OSPF domain. Option A is correct because Hello packets are suppressed. Option C is correct because the prefix is still advertised in LSAs. Option B is incorrect after rewording: it states that the network is not advertised, which is false. Option D is incorrect because passive-interface does not affect data traffic forwarding. Option E is incorrect because the network remains in the OSPF routing table.

Answer

It prevents the router from advertising the network in OSPF LSAs.

Answer

It disables the interface for any OSPF traffic, including data traffic.

Answer

It removes the network from the OSPF routing table.

Question 15

A network engineer is troubleshooting OSPFv3 adjacency between two directly connected Cisco routers, R1 and R2, both running IOS-XE. The engineer configures OSPFv3 on both routers but notices that the adjacency does not form. The engineer runs 'show ospfv3 neighbor' on R1 and sees no neighbors. What is the most likely cause of this issue?

Accepted Answer

The interface GigabitEthernet0/0 is missing the 'ospfv3 1 ipv6 area 0' command.. OSPFv3 requires explicit interface-level configuration to enable the protocol on a specific interface. The correct command is 'ospfv3 1 ipv6 area 0' (or 'ipv6 ospf 1 area 0' for the traditional OSPFv3 configuration). Without this command, the interface does not participate in OSPFv3, so no Hello packets are sent or received, preventing adjacency formation.

Answer

The OSPFv3 process ID must match on both routers.

Answer

The link-local addresses are not in the same subnet.

Answer

The router ID 1.1.1.1 is duplicated on R2.